Refining and bleaching of sugar cane wax



Patented June 2, 1953 UNITED STATES; PATENT OFFICE REFINING AND BLEACHING OF SUGAR CANE WAX corporate No Drawing. Application April 17, 1951, Serial- No. 221,524. In Australia February 7, 1950 6- Claims.1 1 Our invention relates primarily to the refining of sugar cane wax but refers also to an improved -method of bleaching such wax.

It is known-that a crude sugar cane waxmay be extracted from the clarification or filter cake of sugar cane mills by means. of an organic solvent andthat av variety of such solvents may be used forthis purpose. Depending on the type of cane and the processes used at the sugar mill for processing the cane juices, vas well as on the solvents used for extraction, the crude wax contains varying amounts of non-wax components and'varying amounts of ash-yielding material, and may be from green-brown to dark brown in colour. Some of the non-wax constituentsof the crude wax are soft and fat-like in consistency and confer on the wax a sticky nature. Prolonged presence in the filter-cake also. gives rise to a rusty odour in the crude wax.

It has been the aim of many investigatorsrto produce from thiscrude wax a ale, odourless, hard wax, free of the soft fat-like materials and of the ashable matter. It is known that the ashable material can be removed by washing with aqueous mineral acids.- Many processes have been described which seek to remove the softer components and the colour of the crude wax by preferential extraction either of the wax or nonwax components in, a suitable organic solvent. Other processes seek to remove colour by its adsorption from an organic solvent on to a suitable adsorbent earth.

The main object of our invention is to provide an improved method of removing the undesirable softer and fat-like components and a fur ther object is to provide an improved method of bleaching the refined wax.

According to our invention the crude wax, after it has been freed of mineral matter, if present, by digestion with a mineral acid, is distilled under a pressure of not greater than about 6 millimetres of mercury in an inert atmosphere such as steam, carbon dioxide or nitrogen at a temperature which rises above 250 C. and does not exceed 325 C. and which is maintained within that range until the desired proportion of distillate has passed off. The preferred atmosphere is steam. After treatment in this manner, a hardened dark Wax remains as the residue, the undesirable components having passed over 2 with the distillate. This wax is free of objectionable odour. The hard dark wax may then be bleached by chromic acid in sulphuric acid solution to a hard pale wax.

In our invention the object is to remove the softer free fatty acidsand fat-like components of crude sugarcane wax as distillate. These may comprise 40% of the crude wax. A hard dark wax or low acid value then remains. For this purpose the distillation temperatures used range from 250-to 325 C. and distillation pressur is low, lying preferably between 0.5 and 2.0 mm. ofmerc-ury. The hard wax remaining undistilled after this treatment does not suffer serious alteration and'possesses approximately the properties of the hard dark wax obtained by the processes of solvent refining examples of which are given by R. T. Balch in Wax and Fatty Byproducts of Sugar Cane Technological Report No. 3, Sugar'Research Foundation Inc., New York, 1947.

The nature of the hard wax can be varied by adjusting theproportion'oi material distilled. This may be done either by interrupting the distillation or by selecting within the range 250 C.-- 325 C; at temperature at which only the desired percentage of distillatecan distill. Below 250 C. it is not possible to remove the undesirable components except by the use of inconveniently low pressures of the order of 0.01 mm. while above 325 C. the'wax" is'damaged by thermal decomposition. Thus, from an ash-freed crude wax initially having an acid value of a5, a melting point of 69-70 C., and a Brinell hardness of 0.50, after removing 8% at250 C. under a pressure of 1 mm. of mercury, an odourless, dark wax remained having an acid value of 8, a melting point of 73 C. and a. Brinell hardness of only 0.77.. After 38% of the same wax had been removed at 300 C. under 1 mm. pressure, the residual wax had'an acid'value of 3, melted at 74 C. and had the much higher Brinell hardness of 2.23.

Such a refined wax may be bleached by chromic acid in sulphuric acid solution to valuable hard waxes, which, depending on the amount of chromic acid used, may be pale brown to white in colour and have acid values up to 180.

Th undesirable softer components of the wax removed by distillation are obtained by this means in a condition which makes them an attractive by-product. They are pale brown in colour, free of odour, and may be easily collected fractionally by changing the receiver during dis- .4 liquors were withdrawn. The wax and remaining liquors were again stirred and heated while a further 550 ml. of the bleaching solution were added in 4 hours. Heating was continued for 8 hours and again the spent liquors were withtillation. Thus, when three fractions were made during a distillation at 1 mm. pressure, they drawn when the wax had separated. The solid possessed th properties tabulated: was was washed with cold water, then stirred Temperature Melting Saponifi- Percent sari iiiiifi $5111 at; Iii??? as Rising to 260..-. 11 40 183 190 71 9 260-3 11 59 77 83 70 50 300 13 so 63 7s 73 70 This shows that the acidic materials are conand refluxed for 1 hour with 750 ml. of 30% sulcentrated in the first portions of the distillate phuric acid and again the aqueous liquors drawn and that later portions of the disillate consist off after separating. The wax was then washed 3 largely of neutral material. times with cold water, once by refluxing for 1 The invention is illustrated but is not limited hour with 750 ml. of water, allowed to separate, by the following examples. collected, dried in vacuo at 95 C. and flaked.

Example 1 This wax was yellow in colour, melted at 76 0., had an acid value of 120, an iodine value of Crude sugar cane Wax, Obtained by extracting zero and a Brinell hardness of 1.67. It was oba filter cake with a petroleum fraction (Shell X2) tained in a yield f 32 (32%) at its boiling point, was freed of ashable material We claim; by digestion with dilute hydrochloric acid and A method f f ning Sugar cane Wax, with water according to known methofis- It then prising the distilling of undesirable components melted at possessed acld Value of from the crude wax under a pressure not greater and aBnnen hardness than about 6 millimetres of mercury in an inert 400 of the resultant wax were Placed m a 1 atmosphere and at a temperature which rises litre Pyrex flask fitted with a long neck and a above 250 C. and does not exceed 325 C. and wide delivery tube. The flask Was Connected which is maintained within that range until the Suitable receiving Vessels, evacuated 1 desired proportion of distillate has passed off. pressure and heated first at 200 C., increasing A method of r fi i sugar cane wax as the t mpera ur during 1 hour H1300" Steam claimed in claim 1, in which the distillation is was admitted into the flask under the wax at 2, carried out in an atmosphere f steam rate of 2 g. per hour. At the end of 3 hours 30% A method f r f i sugar cane wax as of the wax had distilled and the distillation was claimed in ciaim 1, in which the distillation is terminated and carbon dioxide or nitrogen was 40 carried out at a temperature of about 300 C. admitted to the distillation flask. The residual, A method f refining sugar cane Wax as vacuum-hardened wax was odourless, dark brown claimed in claim 1, and in Which the Wax Which in colour, melted at had an acid Value of remains as the residue is bleached by chromic 6, an iodine value of 37 and a Brinell hardness 11hid in suiphuric acid Soiution. of 1.78. 5. A method of refining sugar cane wax as The distillate when c l e as a Whole was a claimed in claim 1, in which the distillation is pale brown paste W an 201d will8 of 37 and carried out under a pressure between 0.5 and 2.0 an iodine value of 79 and melted at 57 C. It millimetres of mercury could be fractionally collected as above stated. A method of fi i Sugar cane wax as Example 2 claimed in claim 1, in which the softer compo- 100 g of the vacuummardened Wax of 1:211:22 distilled from the wax are fractionally colample 1 were placed in a flanged 3 litre reaction flask fitted with a horse-shoe stirrer and 100 ml. HAROLD HERBERT HATT f 30% w./v aqueous sulphuric acid, but, pref- PETER HERMANN ALOIS 'STRASSER erably, 100 ml. of spent liquor from a previous WILLIAM JOHN TROYAHN bleach, were added. The flask was fitted with a lefiltlJX condenicr 3 groppingl 2 32:31- in gg References Cited in the file of this patent mix ure was s irre an 1e vesse oil-bath to cause refluxing. Chromic acid (90 g.) UNITED STATES PATENTS was then added continuously over a period of Number Name Dat four hours as 833 ml. of a solution containing 2,401,338 Dunmire June 4, 1946 108 g. chromic acid and 420 g. sulphuric acid per litre. After heating and stirring a further 3 FOREIGN PATENTS hours, heating was discontinued and stirring Number r$' Date continued until the temperature reached C. 3 Great rltam 1915 After standing, 830 ml, of the spent aqueous 9,105 Great Blltain 1 93 

1. A METHOD OF REFINING SUGAR CANE WAX, COMPRISING THE DISTILLING OF UNDESIRABLE COMPONENTS FROM THE CRUDE WAX UNDER A PRESSURE NOT GREATER THAN ABOUT 6 MILLIMETERS OF MERCURY IN AN INERT ATMOSPHERE AND AT A TEMPERATURE WHICH RISES ABOVE 250* C. AND DOES NOT EXCEED 325* C. AND WHICH IS MAINTAINED WITHIN THAT RANGE UNTIL THE DESIRED PROPORTION OF DISTILLATE HAS PASSED OFF.
 4. A METHOD OF REFINING SUGAR CANE WAX AS CLAIMED IN CLAIM 1, AND IN WHICH THE WAX WHICH REMAINS AS THE RESIDUE IS BLEACHED BY CHROMIC ACID IN SULPHURIC ACID SOLUTION. 